import java.util.Scanner;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class Main {     public static void main(String[] args) {
        ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
        ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("nashorn");
        String expression = new Scanner(System.in).nextLine();

        try {
            String result = String.valueOf(scriptEngine.eval(expression));
            System.out.println(result);
        } catch (ScriptException e) {
            e.printStackTrace();
        }
    }
}

简单的表达式计算 可以这样吗?   这样犯规了吗?